5W Power Resistors, Cement, Film & Wirewound
5W power resistors for load control, repair and thermal design
This collection focuses on 5-watt resistors in axial film, cement wirewound and aluminum-housed formats. It includes metal film, carbon film, metal oxide, ceramic cement, RX24 wirewound, selected high-voltage and precision low-resistance products, plus single-value packs and assortment kits. Construction varies substantially, so choose by the exact product and variant rather than wattage alone.
What is a 5W resistor?
A 5W resistor is designed to dissipate up to five watts under specified mounting, ambient-temperature and derating conditions. The rating does not by itself define resistance tolerance, working voltage, pulse energy, element material, inductance, dimensions or surface temperature. Calculate circuit dissipation using P = I²R or P = V²/R, then add design margin.
Products represented
- Axial metal film: selected listings specify 1% tolerance across broad resistance ranges.
- Axial carbon film: commonly listed at 5% tolerance for general-purpose repair and prototyping.
- Metal oxide film: through-hole products with construction and overload behavior distinct from carbon and metal film.
- Cement wirewound: ceramic-bodied fixed resistors, including standard values and selected BPR56 multi-wattage listings.
- RX24 aluminum-housed wirewound: chassis-oriented products requiring suitable mounting and heat transfer.
- RI80 glass-glaze high-voltage: specialized 3W/5W variants whose voltage capability must be checked product by product.
- BWL precision low-resistance: selected 3W/5W/10W options with listing-specific tolerance, TCR and non-inductive claims.
- SMD alloy sampling parts: mixed 2512, 3920 and 5930 options from 3W to 7W, not one common footprint or rating.
How to select a 5W resistor
- Choose resistance: distinguish Ω, R, K, M and milliohm notation. Confirm decimal placement before ordering.
- Select the exact 5W option: many listings also contain 1/8W through 3W, 10W, 25W, 50W, 100W or other variants.
- Calculate continuous dissipation: include margin for enclosure temperature, airflow and nearby heat sources.
- Verify construction: metal film, carbon film, metal oxide, cement wirewound, aluminum-housed and alloy elements are not equivalent.
- Check tolerance and TCR: these are independent specifications and apply only where stated for the selected variant.
- Check voltage and pulses: maximum working voltage, overload duration and pulse-energy limits can govern before 5W is reached.
- Confirm mechanics: compare body dimensions, lead spacing, mounting holes or the exact SMD land pattern.
Axial, cement and aluminum-housed differences
Axial film resistors are convenient for through-hole boards but need lead spacing and hot-body clearance. Cement resistors use a ceramic enclosure and are often wirewound, but the enclosure does not guarantee non-inductive behavior. RX24 aluminum-housed resistors are intended to transfer heat through their case; their full rating may depend on secure mounting to a suitable heat sink or chassis.
Continuous power and thermal derating
A 5W label is not permission to run every part continuously at 5W in free air. Review the product's derating curve, ambient rating and mounting instructions. Allow for enclosure heating, airflow, PCB discoloration, lead temperature and safe clearance from plastics, wiring and electrolytic capacitors.
Low-resistance and current-sense boundaries
A low resistance value does not automatically make a component a precision current shunt. Verify tolerance, TCR, element material, overload stability and terminal geometry. At milliohm levels, solder joints and copper traces can dominate measurement error; Kelvin routing or four-wire measurement may be required.
High-voltage and pulse boundaries
RI80 and other high-voltage products must be selected by working voltage, body dimensions, creepage, clearance and environment. A 5W rating alone does not establish high-voltage suitability. Discharge, braking, dummy-load and startup applications also require pulse-energy and duty-cycle data.
Collection boundaries
Assortment listings may combine many wattages, so order the exact 5W variant and verify the value list and quantity per value. Mixed SMD listings contain 2512, 3920 and 5930 parts with different sizes and 3W–7W claims; they are not interchangeable. A 0603 1/10W listing and several 1/2W or 1/4W kits are included in the collection but are not 5W substitutes. Product titles referencing Welwyn, UK, high fidelity or other brands and applications do not by themselves prove manufacturer authorization, authenticity, certification or audio performance.
Typical applications
- Power-supply bleeders, ballast and current limiting
- Through-hole equipment repair with matched dimensions
- Amplifier bias, emitter or source resistance
- Motor, relay and solenoid suppression networks
- Prototype load banks using verified thermal margins
- Low-ohm sensing with suitable element and Kelvin layout
- High-voltage dividers using purpose-rated parts and safe spacing
Ordering checklist
- Resistance value and notation
- Exact 5W variant and pack quantity
- Element technology and package style
- Tolerance and TCR
- Working voltage and overload or pulse rating
- Body size, lead spacing, mounting holes or SMD footprint
- Required heat sink, chassis contact, airflow and derating
- Assortment value list and quantity per value
Frequently asked questions
Can every 5W resistor dissipate 5W continuously?
No. Continuous capability depends on ambient temperature, mounting, airflow and the manufacturer's derating conditions.
Can a 5W resistor replace a lower-wattage resistor?
Sometimes, after checking resistance, tolerance, dimensions, voltage, pulse behavior and circuit requirements.
Is a cement resistor automatically non-inductive?
No. Many cement resistors are wirewound. Non-inductive construction must be stated for the exact product.
Does an RX24 aluminum case provide its own heat sink?
No. The case helps conduct heat, but the rated power may require mounting to an appropriate chassis or heat sink.
Are all low-ohm products precision current-sense resistors?
No. Confirm tolerance, TCR, construction, overload data and recommended measurement geometry.
Does 5W prove high-voltage capability?
No. Working voltage, creepage, clearance and transient ratings are separate limits.
Are 2512, 3920 and 5930 SMD resistors interchangeable?
No. They differ in dimensions, land patterns, thermal paths and possible power ratings.
Are all products in this collection rated 5W?
No. Some shared listings contain other wattages or unrelated lower-power options; verify the selected variant before purchase.
